Rationale: Few studies have investigated childhood respiratory outcomes of intrauterine growth retardation (IUGR), and it is unclear if catch-up growth in these children influences lung function.

Objectives: We determined if lung function differed in 8- to 9-year-old children born at term with or without growth retardation, and, in the growth-retarded group, if lung function differed between those who did and those who did not show weight catch up.

Methods: Caucasian singleton births of 37 weeks or longer gestation from the Avon Longitudinal Study of Parents and Children (n = 14,062) who had lung spirometry at 8-9 years of age were included (n = 5,770).

Measurements and main results: Infants with gestation-appropriate birthweight (n = 3,462) had significantly better lung function at 8-9 years of age than those with IUGR (i.e., birthweight <10th centile [n = 576] [SD differences and confidence intervals adjusted for sex, gestation, maternal smoking during pregnancy, and social class: FEV(1), -0.198 (-0.294 to -0.102), FVC, -0.131 (-0.227 to -0.036), forced midexpiratory flow between 25 and 75% of vital capacity -0.149 (-0.246 to -0.053)]). Both groups had similar respiratory symptoms. All spirometry measurements were higher in children with IUGR who had weight catch-up growth (n = 430) than in those without (n = 146), although the differences were not statistically significant. Both groups remained significantly lower than control subjects. Growth-retarded asymmetric and symmetric children had similar lung function.

Conclusions: IUGR is associated with poorer lung function at 8-9 years of age compared with control children. Although the differences were not statistically significant, spirometry was higher in children who showed weight catch-up growth, but remained significantly lower than the control children.